Syntax:
ROUND(X), ROUND(X,D)

Rounds the argument X to D decimal places. The rounding algorithm
depends on the data type of X. D defaults to 0 if not specified. D can
be negative to cause D digits left of the decimal point of the value X
to become zero.

URL: http://dev.mysql.com/doc/refman/5.7/en/mathematical-functions.html

